1. Technical Field
The present invention relates to a sample analysis element, a detecting device, and the like that are provided with a metallic nano-body such as a metallic nanoparticle or a metallic nano-projection.
2. Related Art
A sample analysis element using localized surface plasmon resonance (LSPR) is known. Such a sample analysis element is provided with metallic nano-bodies, that is, metallic nanoparticles which are dispersed on, for example, a dielectric surface. The metallic nanoparticle is formed sufficiently smaller than the wavelength of excitation light, for example. If the metallic nanoparticle is irradiated with the excitation light, an electric dipole is induced on the particle and an electric field is generated around the particle. As a result, a strong local electric field due to the interaction between the electric dipoles is generated between the metallic nanoparticle and the metallic nanoparticle. Such a site is called a hot spot.
In Yizhuo Chu et al, “Experimental study of the interaction between localized and propagating surface plasmons”, OPTICS LETTERS, U.S.A. Feb. 1, 2009, Vol. 34, No. 3, p. 244-246, the metallic nanoparticles are disposed in a lattice form at a predetermined pitch. If the size of the pitch is set to be a specific numerical value, propagating surface plasmon (PSP) based on an evanescent wave occurring. The propagating surface plasmon is combined with the localized surface plasmon, and thus a so-called hybrid mode is established. The localized surface plasmon resonance is further enhanced through the combination, and thus, near-field light that is generated on the surface of the metallic nanoparticle is further intensified.
JP-A-2009-222401 is an example of related art.
The sample analysis element described above can be used in a target substance detection device. However, as disclosed in Yizhuo Chu et al, “Experimental study of the interaction between localized and propagating surface plasmons”, OPTICS LETTERS, U.S.A. Feb. 1, 2009, Vol. 34, No. 3, p. 244-246, since the wavelength of the evanescent wave that causes the propagating surface plasmon resonance is determined by an array pitch of the metallic nanoparticle, the surface density of the hot spot on the dielectric surface is reduced. For this reason, establishment to detect target substance at the hot spot becomes very low, and thus it is not possible to realize a high sensitive sample analysis element and a detecting device.